APPLICATION NOTES for Through Hole LED Display

The full text of these application notes is reproduced below so it can be read and searched directly. The original PDF (202004 version) is available for download at the end of this page.

1. Scope

LEDs are suitable for general electronic products. In the event that the product needs to be applied to certain special reliability requirements, as well as when product failure may endanger life and health equipment, it is necessary to contact Opto Plus LED Corp.

2. Environment

Through hole LEDs must avoid continuous exposure to a condensing moisture environment, and must be kept away from rapid temperature changes.

3. Storage Conditions

Through hole LEDs must be stored at a temperature below 30°C and humidity below 60%RH.

4. After Opening

After the original sealed package has been opened, through hole LEDs should be assembled within 72 hours.

5. Baking

Baking before soldering is recommended when the package has been unsealed for more than 72 hours and up to 1 week. The conditions should be 30 (±10) hours at 85 ~ 100°C.

6. Oxidized Leadframes

If the storage conditions do not meet specification standards, or the parts are kept in a high humidity environment, the leadframe will become discolored and oxidized. Once the leadframe has become discolored and oxidized, re-plating and re-sorting before use is suggested. We suggest customers use LEDs as soon as possible and avoid long-term storage of large inventories.

7. Soldering General Notes

• A lamp without a stopper type must have a minimum of 3 mm clearance from the base of the lens to the soldering point when soldering.
• Do not apply any external stress to the leadframe during soldering while the LED is at high temperature.

Note: excessive soldering temperature and/or time might result in deformation of the LED lens or catastrophic failure of the LED.

• A pre-heat temperature of 100°C or less is recommended (as measured with a thermocouple attached to the LED pins) prior to immersion in the solder wave, with a maximum solder bath temperature of 260°C.
• Peak wave soldering temperature between 245°C ~ 255°C for 3 sec (5 sec max.).
• Do not apply stress to the epoxy resin while the temperature is above 85°C.
• No more than one wave soldering pass.
• Manual soldering is not recommended unless necessary, such as when repair or rework is required.
• Soldering iron power shall not exceed 30 W. The recommended maximum temperature for lead soldering is 300°C for Pb-Sn solder and 350°C for lead-free soldering. For blue (typical λd 465 nm), green (typical λd 525 nm), and all white LEDs, the maximum soldering iron temperature is 280°C. Do not place the soldering iron on the component for more than 3 seconds.
• The tip of the soldering iron should never touch the lens epoxy.
• Do not apply stress to the leads when the component is heated above 85°C, otherwise internal wire bonds may be broken.
• After soldering, allow at least three minutes for the component to cool down to room temperature before further operations.

8. LED Mounting Method

The lead pitch of the LED must match the pitch of the PCB holes during component assembly. Lead forming is needed to ensure the lead pitch matches the hole pitch. Refer to the figure at the top of this page for the proper lead forming procedures.

9. Lead Forming Procedures

• Reserve a minimum of 3 mm clearance between the base of the LED lens and the first lead bend.
• Lead forming must be done before soldering, at normal temperature.
• During lead forming, use tools or jigs to hold the leads securely so that the bending force will not damage the LED lens or its internal structures. Do not perform lead forming once the component has been mounted onto the PCB.
• Do not bend the leads more than twice.
• During assembly on the PCB, use the minimum force possible to avoid excessive mechanical stress.

10. Repairing

Repair should not be done after the LEDs have been soldered. When repairing is unavoidable, we suggest using a double-head soldering iron. It should be confirmed whether the characteristics of the LEDs will be damaged by repairing.

11. Cleaning

• Use alcohol-based cleaning solvents such as isopropyl alcohol to clean the LEDs if necessary.
• Do not use acidic solvents or unknown chemicals, as they might cause corrosion or damage to the component.
• Do not soak the component in solution.

12. ESD (Electrostatic Discharge)

Static electricity or a power surge will damage the LED, especially for InGaN/GaN products. We suggest preventing ESD damage in the working area as below.

• Use a conductive wrist band or anti-electrostatic glove when handling these LEDs.
• All devices, equipment, and machinery must be properly grounded.
• Work tables, storage racks, etc. should be properly grounded.
• Avoid handling by hand without antistatic garments and wrist straps, and avoid the use of common plastic containers, transport mediums or tools.
• Use an ionizer to neutralize the static charge which might have built up on the surface of the LED lens as a result of friction between LEDs during storage and handling.
• All workstations that handle IC and ESD-sensitive components must maintain an electrostatic potential of 150 V or less.
• Relative humidity levels maintained between 40% and 60% in the production area are recommended to avoid the build-up of static electricity.

13. Circuit Design Notes

• An LED is a current-operated device. In order to ensure intensity uniformity across multiple LEDs connected in parallel in an application, it is recommended that a current-limiting resistor be incorporated in the drive circuit, in series with each LED. Without one, the brightness of each LED might appear different due to the differences in the I-V characteristics of those LEDs.
• The customer’s PCB circuit should be designed to avoid reverse voltages and transient voltage spikes when the circuit is powered up or shut down.
• It is recommended to operate LEDs at the binning current of 20 mA to reduce visible differences in color and intensity. If LEDs are to be driven at a very small current (e.g. 2 mA or 5 mA), please contact Opto Plus first.
• Please refer to the current vs. temperature graph on the datasheet for the current limit at each temperature.

14. Restrictions on Product Use

• If a reverse bias is continuously applied to LEDs, it can cause damage.
• The information contained within this document is subject to change without notice. Before referencing this document, please confirm that it is the most current version available.
• Not all LED types are available in every country.
• The light output from UV, blue, and white LEDs may cause injury to the human eye when viewed directly.
• Prolonged reverse bias should be avoided, as it could cause LEDs to develop leakage current or a short circuit.
• Excess driving current and/or an operating temperature higher than the conditions recommended in the specification may affect the life of the LEDs.

15. Terms and Conditions for the Usage of This Document

• The information included in this document reflects representative usage scenarios and is intended for technical reference only.
• The part number, type, and specifications mentioned in this document are subject to future change and improvement without notice. Before production usage, the customer should refer to the latest datasheet for the updated specifications.
• When using the products referenced in this document, please make sure the product is being operated within the environmental and electrical limits specified in the datasheet. If customer usage exceeds the specified limits, OPTO PLUS will not be responsible for any subsequent issues.
• The information in this document applies to typical usage in consumer electronics applications. If the customer’s application has special reliability requirements or life-threatening liabilities, such as automotive or medical usage, please contact an OPTO PLUS representative for further assistance.
• All through hole LED operation should refer to the datasheet and these application notes.